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    <title>Document</title>
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    <script>
   //根据位置返回字符
   //1.charAt(index) 根据位置返回字符
   var str = 'daqj';
   console.log(str.charAt(2));
   //遍历所有字符
   for (var i = 0; i < str.length; i++){
       console.log(str.charAt(i));
   }
   //2.charCodeAt(index) 返回相应索引号的字符ASCII值 目的：判断用户按了哪个键
   console.log(str.charCodeAt(0));


   for (var i = 0; i < str.length; i++){
    console.log(str.charCodeAt(i));
   }

   //3. str[index] H5新增的
   console.log(str[0])
    </script>
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